Conducting polymers for coatings and antielectrostatic applications

ABSTRACT

A processable electrically conductive polymeric complex comprising a polyelectrolyte having acid functional groups and a conductive polymer selected from the group consisting of polyaniline, polypyrrole, polythiophene, poly(phenylene sulfide), the conductive polymer ionically bound to the polyelectrolyte. The mole ratio of the monomers which form the conductive polymer to the acid functional groups of the polyelectrolyte is ≧1. The polymeric complex is made by a template-guided chemical polymerization process which comprises adsorbing the monomers onto the polyelectrolyte in a mixture of alcohol and water to form a polyectrolyte adduct, emulsifying the polyelectrolyte adduct in an acid to form an emulsified polyelectrolyte adduct and oxidatively polymerizing the emulsified polyectrolyte adduct. The polymeric complex is water insoluble when dried as a coating on a substrate.

This application claims the benefit of provisional application Ser. No.60/063,766 filed Oct. 29, 1997.

FIELD OF THE INVENTION

The invention relates to an electrically conductive polymeric complexwhich can be coated on the surfaces of plastics, metals and fibers, orembodied in other polymeric or inorganic materials.

BACKGROUND AND BRIEF SUMMARY OF THE INVENTION

Electrically conductive coatings are used for no-shock rugs, no-clingfabrics, antielectrostatic coatings for packaging materials, lowemissitivity garments for better insulation value or infrared camouflageand as antielectrostatic coatings for plastics, glass and othersurfaces. The prior art coatings for these purposes are typically ionicconductors or electronic conductors.

Ionic conductors include quaternary ammonium salts and polyelectrolytes.The drawbacks to the effective uses of these conductors are lowconductivity and surface resistivities 10⁹ to 10¹³ ohm per square. Theresistivity is humidity sensitive, such that the ionic conductivity isgreatly decreased in dry environments.

Electronic conductors, e.g. carbon fibers and antimony-doped tin oxidemixed in polymeric fibers, perform better than ionic conductors becausethey can achieve higher conductivity and are not as sensitive tohumidity levels. However, electronic conductors result in a materialwhich is stiff, fragile and difficult to process. Further, theelectronic conductors are difficult to dye.

Intrinsically conducting polymers are not only useful forantielectrostatic applications, they are potentially useful in otherfields. They are potentially useful as anticorrosion coatings because oftheir electroactive interaction with the metal surface. A coating may beapplied to windows of a car or a building to reduce heating by sun lightbecause the polymer is effective to prevent the transmission of the nearinfrared region of the solar radiation while allowing the visible lightto pass through. A coating or a fabric-like material that contains theconducting polymer may modify the emissivity of a warm body (human or avehicle) to camouflage against the detection of night-vision sensors. Amaterial containing a conducting polymer for these applications needsboth to be easily applied as a coating material and to be durable as acoating.

Conducting polymers such as single strand polyaniline, have not enjoyedcommercial success. They are brittle, very difficult to process and notstable in the conductive state.

A molecular complex of polyaniline and a polyelectrolyte which isprocessable, is disclosed in U.S. Pat. No. 5,489,400. As disclosed inthis patent, the mole ratio of aniline monomer to the acid functionalgroup (polyelectrolyte) was less than one. When the mole ratio wasincreased beyond one, the molecular complex become insoluble in solventsand was difficult to use in coating or dying processes. Further, theelectrical conductivity of the molecular complex disclosed in thatpatent diminished when the molecular complex was used in a dye orcoating.

The present invention is directed to a polymeric complex of a conductingpolymer and a polyelectrolyte where the mole ratio of the conductingpolymer to the acid functional groups of the polyelectrolyte is greateror equal to one. The polymeric complex described herein is easilyprocessable for coating and mixing applications.

The invention, in another embodiment, is directed to the method ofsynthesizing the polymeric complex.

The invention in still another embodiment relates to the coatings andcompositions based on the polymeric complex.

The present invention discloses a new processable electricallyconducting polymer complex and a synthesis for making the same. Theseprocessable complexes comprise certain polyelectrolytes and a conductingpolymer. The polymeric complex is made by template guided chemicalpolymerization and contains a polyelectrolyte and a conducting polymer.The polyelectrolyte carries a net negative electrical charge and theconducting polymer carries a net positive electrical charge.Alternatively, the polyelectrolyte can carry a net negative electricalcharge and the conducting polymer is in its non-conductive electricallyneutral state. Optionally, the polyelectrolyte carries a net positiveelectrical charge and said conducing polymer in its nonconductiveelectrically neutral state. In addition, the polymeric complex of thisinvention can comprise at least two types of polyelectrolyte and onetype of conducting polymer.

The polymeric complex is an electrically conducting complex which issuspendable in water. The complex is easily processed such that it canreadily be applied by a coating, brushing, spraying, roller, etc. Thepolymeric complex is washable whether admixed with other polymers orcoated on fabrics or hard surfaces. Alternatively, the molecular complexcan be admixed with other materials such as epoxy, poly(vinyl butyreal)and NYLON® as polymer blends.

This invention, in one embodiment, relates to a synthesis that leads tothe conducting polymeric complex that is a suspension or dispersion inwater or aqueous solution. It is processable as a water-borne coatingmaterial. The water-borne conducting polymer is, however, insoluble inwater once it is dried as a coating on a substrate. This property makesit advantageous. Although the prior art teaches polymeric complexes canbe made soluble in water, so a coating can be also made by evaporationof the water, the coating is not durable because it is easilyredissolved by water. The truly water soluble conducting polymers cannot be used as antielectrostatic coatings if the surface is to be incontact with water or moisture. The prior art water soluble polyanilineis also not useful as anticorrosion coating materials because of theextensive swelling or dissolution in ambient environment.

In a preferred embodiment, the invention is a double strand conductingpolymeric complex. One strand is a conducting polymer, preferablypolyaniline, which has high electrical (not ionic) conductivity. Theother stand is a polyelectrolyte which provides the sites forfunctionalities. The polyelectrolyte also provides stability to theconducting polymer, processability to the conducting polymer andmaintains the conductivity of the conducting polymer in saline water,moisture and solvents, environments of high temperatures, e.g. 200° C.The mole ratio of the aniline to the functional group is greater than1:1 and the polymeric complex can be suspended in a water orwater/alcohol mixture. The ratio of the aniline to acid functional groupcan be increased to more than 4:1 while still maintaining the propertiesof processability.

The polyelectrolyte is selected to provide adhesion to textile fiberseither by absorption into the fibers, by chemical binding, or by polymerchain tangling or interlocking with the fibers. The conducting polymerresists water induced protonation and is washable in neutral water.Typically prior art conducting polymers deprotonate in water.

The polymeric complex of the invention is an aqueous based compositionand can be applied by painting, spraying, dipping, screen printing orany of the known coating techniques, i.e. roll to roll, doctor blade,etc. The complex is suspended as microaggregates in water and isblendable with other polymers or dyes.

The polymeric complexes disclosed herein have higher electricalconductivity than the molecular complexes of the prior art and are stillprocessable (blendable and dispersible).

BRIEF DESCRIPTION OF THE DRAWING(S)

The FIGURE is a graphical representation of the conductivity achievedwith a coating of the invention on a fabric.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The polymeric complex embodying the invention comprises a first strandof a conducting polymer and a second strand of a polyelectrolyte.

The first strand is selected from the group consisting of polyaniline,polypyrrole, polythiophene, poly(phenylene sulfide), poly(p-phenylene),poly(carbazole), poly(thienylene vinylene), polyacetylene,poly(isothianaphthene) or the substituted versions thereof.

The second strand polyelectrolytes are selected from the groupconsisting of poly(acrylic acid) PAA; poly(vinylmethylether-co-maleicacid) (PVME-MA); poly(vinylalkylether-co-maleic acid;poly(ethylene-co-maleic acid); and structurally and functionallyequivalent polyelectrolytes.

In the synthesis of the double strand polymeric complex, a mixed solventsystem is used which allows a higher conducting monomer topolyelectrolyte mole ratio to be achieved without the reactants and theproducts (first and second strands) coagulating or precipitating out ofthe reaction solution.

As described hereinafter, highly conductive and processable polyanilineis (first strand) achieved by the use of (second-strand)polyelectrolytes not previously used with polyaniline in a polymericcomplex.

Synthesis of the molecular polymeric complex of polyaniline:poly(vinylmethylether-co-maleic acid) PANI:P(VME-MA).

The polymeric complexes synthesized in the next six examples represent aclass of polymeric complexes of polyaniline and a copolymer thatcontains carboxylic acid functional groups. A structure of this type ofpolymeric complex is shown.

In the polymeric complex the ratio r=N_(AN)/N_(—COOH) is a variable thatcan be controlled by the template guided synthesis which is described inthe literature and the aforementioned patient. Here N_(AN) is the numberof aniline monomer units in the polymeric complex, and N_(—COOH) is thenumber of the carboxylic functional groups A⁻ in the same polymericcomplex. The r value for the prior art molecular complex was r<1.

The following examples describe the synthesis and the materialproperties for the molecular complexes where r=1, 2, 3 and 4. Thesecomplexes are aqueous-based and the coatings formed are moreelectrically conductive than the prior art coatings. Furthermore, thecoating, after the water is evaporated, is not dissolved or dedoped bycontact with water.

EXAMPLE 1

Synthesis of Polyaniline: poly(acrylic acid) complex withr=N_(AN)/N—_(COOH)=1, [Polyaniline:poly(acrylic acid), r=1]. Here we usethe symbol : to indicate the non-covalent bonding between two polymers.The value of r is included to specify the ratio N_(AN)/N_(—COOH).)

Step 1: Adsorption of aniline onto poly(acrylic acid) to prepare[poly(acrylic acid):(Aniline)_(n)]:

In this step a complex of [poly(acrylic acid):(Aniline)_(n)]: wasprepared by adsorbing (or binding) the aniline monomer onto thepoly(acrylic acid) in a water/methanol solution. The adsorbed anilinemolecules are polymerized later into polyaniline in Step 3.

10 ml of methanol was mixed with 7.208 gm of poly(acrylic acid) aqueoussolution (containing 25% of PAA, Polyciences, MW=90,000). Water wasadded to increase the volume of the solution to 100 ml. This solutionwas rigorously stirred which a magnetic stirrer for 15 minutes. Thissolution contained 0.025 moles of poly(acrylic acid). 2.328 g of freshlydistilled aniline was slowly added to the poly(acrylic acid) solutionunder rigorous stirring. An additional 10 ml of methanol was added.Stirring was continued for 30 minutes. The total amounts of anilineequaled 0.025 mole. The mixture had a pH value of about 5.

The following observations are consistent with the formation ofpolymeric complex between the aniline molecules and the poly(acrylicacid). The viscosity of the solution was significantly increased uponthe addition of aniline. The measured increase in intrinsic viscosity ismuch more than that expected from a simply mixture of aniline andpoly(aniline acid). For a simple mixture with no binding between acrylicand the acid, the viscosity should be about equal to the sum of the twocomponents in pH 5 solution. The high viscosity is consistent with thebinding of aniline onto the poly(acrylic acid) chain. When aniline isadsorbed onto poly(acrylic acid), the polymer chain is more extendedthan that of the original in a poly(acrylic acid), random coil, and thusthe viscosity is much higher. The aniline molecules can bind topoly(acrylic acid) by hydrogen bonding, or the anilinium ions may bestrongly attracted by the electrostatic force form the ionized portionof the poly(acrylic acid). The later electrostatic attraction is knownas “counter ion condensation”for polyelectrolytes (Reference: G.Manning, J. Chemical Physics, 89, 3772 (1988), Accounts of ChemicalResearch, 12, 443 (1979)). The non-covalent binding between the anilinemonomers and the poly(acrylic acid) is represented by a color; thesymbol for the adduct poly(acrylic acid):(AN)_(n).

Step 2: Formation of emulsified poly(acrylic acid):(AN)_(n) adduct.

100 ml of 2 m HCl was added to the poly(acrylic acid):aniline solution.The solution turned milky white immediately due to the scattering of theambient light by a macro-emulsion of the polymeric complex. (When thesolution was continuously stirred vigorously, the intensity of lightscattering decreased and the color of the scattered light graduallychanged from milky white to nearly transparent with a tint of turbidity.When this faintly turbid solution was examined by illumination with afocused beam of white light (or sun light) and viewed at an angleagainst a dark background, the scattered light had a blue tint.

The solution initially turns to milky white macro emulsion because theacid added to the solution decreased the degrees of ionization of thepoly(acrylic acid):(AN)_(n) adduct formed in Step 1. The unionizedadduct becomes more hydrophobic and folds into particles that contain aninterior hydrophobic core that is rich in aniline adsorbed to thepoly(acrylic acid). The exterior surface of the particles may be morehydrophilic with some ionized carboxylate groups in contact with thesurrounding water molecules. The emulsified particle in this case islikely to be an aggregate of the polymeric adduct poly(acrylicacid):(AN)_(n) which is hydrophobic if the aniline molecules remainbounded to the poly(acrylic acid) when the hydrochloride acid is added.Immediately after the addition of the hydrochloric acid, the size of theaggregated particle is large, but the aggregate rearrange into smallerparticles in the methanol/water solution.

The change in light scattering is consistent with an initial formationof a macro-emulsion that scatters visible light of all colors, and thesubsequent transformation into micro emulsion with smaller particle sizethat scatters only the shorter wavelength region of the visible light.The presence of methanol or other polar organic solvents helps to breakthe initial macro-emulsion into smaller particles. The small particleis, to some extent, similar to the micro emulsions found in emulsionpolymerization for the production of latex (Blackely, D. C., EmulsionPolymerization, Wiley, N.Y., 1975; Calvert, K. O., Polymer Latices andtheir Applications, MacMillan, N.Y. (1982)). Unlike the ordinaryoil-in-water emulsions, the hydrophobic core in the polymeric complexesprepared is not only a microscopic droplet of aniline, but it is acomplex of aniline adsorbed on the poly(acrylic acid) backbone. Thepoly(acrylic acid):(An)_(n) adducts may aggregate or fold to form ahydrophobic core, and the ionized carboxylic acid groups are presumblylocated at the interface with water. In this emulsified poly(acrylicacid):(An)_(n) adduct, the poly(acrylic acid) molecule serves two roles:(1) it serves as a template polymer that binds the monomer of the secondpolymer to form a precursor for the polymeric complex[Polyaniline:poly(acrylic acid), R=1]; and (2) it serves as anemulsifier that helps to absorb the aniline monomers in the interior ofthe emulsified particle.

Step 3: Polymerization of the emulsified poly(acrylic acid):(An)_(n)adduct

3 drops of 1 M aqueous ferric chloride (FeCl₃ in 2 M hydrochloric acid)were added to the solution prepared in step 2. 3 ml of 30% hydrogenperoxide (0.026 mole of H₂O₂ were added to the mixture with constantstirring. The solution immediately turned to a dark green colorindicating that the aniline monomers are polymerized into polyaniline.The ferric ion in the solution is a catalyst for the oxidativepolymerization. The reaction was essentially completed within 30minutes. The reaction mixtures were stirred for another 30 minutesbefore starting the purification steps. The reaction product stayed inthe aqueous solution for months with no significant precipitation of thereaction product.

Repeated experiments showed that the use of methanol/water mixed solventin Step 1 is important. Without an adequate amount of methanol, duringthe preparation stage of step 1, the final product in step 3 willprecipitate either immediately or within a week. With the addition ofmethanol, ethanol, or some other organic polar solvents, the product ofstep 3 may be indefinitely suspended in the solution. The polar organicsolvent mixture is only needed for the preparation of the micro emulsionof the precursor poly(acrylic acid):(An)_(n) adduct before thepolymerization step, it is not needed for stabilizing the polymerizedproduct. The entire amount of methanol in the reaction product of step 3can be removed without causing the reaction product[Polyaniline:poly(acrylic acid), r=1] to precipitate.

The methanol was removed by dialyzing against a large volume of water tosignificantly reduce the concentration of methanol, or by heating thesolution to evaporate methanol. The role of methanol might be to reducethe particle size during step 2 so that the polymerized final product issuspendable in water. If step 3 were carried out before the white macroemulsion had enough time to change to the transparent micro emulsion,the reaction produce would not be stably dispersed in water but wereprecipitate within a day or two. This indicates that the transformationfrom the macro emulsion to micro emulsion is important to the formationof water-borne polymer complex. In a variation of the above procedure,the methanol was not added in step 1, but was added at the beginning ofstep 2. This modified procedure also produce water-borne polyanilinecomplexes that are stable in aqueous solution supporting the theory thatthe function of methanol is to facilitate the reduction of the particlesize of the emulsified precursors.

Experiments showed that it is best to start the polymerization step 3within a short amount of time (within a few hours) after the white macroemulsion is changed to bluish tinted micro emulsion in step 2. When thesolution or step 2 is left for days before carrying out step 3, thereaction product is a precipitate and is mostly chloride dopedpolyaniline instead of the polyaniline:poly(acrylic acid) complex. Thismay be due to the extraction of the aniline molecule from the microemulsion into the aqueous phase to form anilinium ions. The microemulsion produced in step 2 is probably at a metastable state instead ofbeing in the equilibrium state of the solution.

EXAMPLE 2

Synthesis of Polyaniline: poly(acrylic acid) complex withr=N_(AN)/N_(—COOH)=1.5, [Polyaniline:poly(acrylic acid), r=1.5].

In this example, the aniline content is increased to r>1 to obtainstable suspension (or emulsion) in water.

Step 1: Adsorption of aniline onto poly(acrylic acid) to prepare[poly(acrylic acid):(Aniline)_(n)]:

7.208 gm of 25% by weight of poly(acrylic acid) (from Polyciense,MW=90,000) was added to 10 ml of methanol, then water was added to make100 ml of poly(acrylic acid) solution. This solution was transferred toa round bottom flask with a magnetic stirrer and continuous rigorousstirring was initiated for 15 min. (Total # of moles of carboxylic acidfunctional groups=0.025 mole).

3.492 gm of freshly distilled aniline was slowly added to thepoly(acrylic acid) solution under rigorous stirring. An additional 10 mlof methanol was added. Stirring was continued for an additional 30minutes. All solid materials were dissolved at this time. (Total amountof aniline equals 0.038 mole). The viscosity of the solution wassignificantly increased after the addition of aniline.

Step 2: Formation of emulsified poly(acrylic acid):(An)_(n) adduct

100 ml of 2 M HCl was added to the poly(acrylic acid):aniline solution.A turbid solution was initially formed. The solution was milky whiteimmediately after the addition of the hydrochloric acid due to thescattering of the ambient light by the macro-emulsion of the polymericcomplex. When the solution was continuously stirred vigorously, theintensity of light scattering decreases and the color of the scatteredlight changed from white to transparent with slightly tinted turbidity.

Step 3: Polymerization of the emulsified poly(acrylic acid):(An)_(n)adduct

3 drops of 1 M aqueous ferric chloride (FeCl₃) in 2 M hydrochloric acidwas added to the reaction mixture 4.4 ml of 30% hydrogen peroxide (0.039mole of H₂O₂) was added to the reaction mixture with constant stirringfor an additional hour. The liquid was dark green in color. The reactionproduct stayed in the aqueous solution for months with no significantprecipitation of the reaction product.

The green-colored aqueous solution contains a stable suspension of thereaction product. The suspension is stable indefinitely. Negligibleamount of the product precipitates from the solution on standing for along period of time. The solution can be filtered through filter paperswithout significant loss of solid material. When 1 ml of the solutionwas diluted with slightly acidic distilled water (0.01 M HC) thesuspension remained stable. This dilute solution showed scattering oflight indicating it was a colloidal suspension.

A contrast can be seen by comparing this solution with a solution fo thepolyaniline: poly(styrene sulfonic acid) complex (r=0.5) (see Example 11below) which shows negligible light scattering at the sameconcentration. It has previously established that thepolyaniline:poly(styrenesulfonic acid) molecular complex is dissolved inwater is a true solution.

The suspension remains stable upon heating in a water bath at 70° C.When the water vapor was allowed to escape from the container of thesolution, the total volume of the solution was reduced and a high solidcontent solution was formed. Water-borne suspensions with 30% solidcontent was found to be stable against precipitation.

The suspension was completely precipitated by addition of an equalvolume of acetone. This property is similar to the common water-bornelatex paints.

The following test shows that the suspension of[polyaniline:poly(acrylic acid)](r=1.5) has a property similar to alatex suspension which is suspendable in water but is insoluble after itis painted on a surface and then is allowed to dry.

The polymeric complexes (green colored liquids) with solid contentranging from 105 to 30% were painted on glass slides, a sheet ofpoly(methylmethacrylate), and a coupon of aluminum alloys. Thegreen-colored paint was dried in the air at room temperature. The driedfilms stay on the surface of the substrates with varying degree ofadhesion. These films were immersed in water for 24 hours, the filmremained as a solid and showed no sign of being dissolved. A comparativetest was performed with a [polyaniline:poly(styrenesulfonic acid),r=0.5] complex (see Example 11) which is a water soluble polymer complexprepared by a method of the prior art. The film coated with[polyaniline:poly(styrenesulfonic acid), r=0.5] complex is completelydissolved in water within 10 minutes. This test shows the utility of thewater-borne [polyaniline:poly(acrylic acid), r=1.5]. It can be used as awater-borne coating material, but the dried coating stays permanent andresists wash off by water or other solvents.

The procedure outlines in Examples 1 and 2 may be applied to thesynthesis of other polymeric complex of polyaniline to producelatex-like water-borne suspension of the reaction product. The followingexamples show the synthesis of the molecular complex of[polyaniline:poly(vinlymethylether-co-maleic acid), r=1 to 4] and theanalysis of the composition of the reaction products.

EXAMPLE 3

Synthesis of [PAN:PVME-MA, r=1]

1.92 gm of poly(vinylmethylether-co-maleic acid)m, PVME-MA, (containing0.022 moles of carboxylic functional groups, Aldrich, M.W.=67,000) wasdissolved in 25 ml of distilled water. 5 ml of methanol was added andslowly 2 gram of aniline (0.022 mole of aniline) was added to thissolution and stirred for one hour. At this stage, aniline was adsorbedon PVME-MA to form the adduct [poly(vinylethylether-co-maleicacid):(An)_(n).

25 ml 3 M HCl and 6.0×10⁻⁴ mole of ferric chloride was slowly added tothe solution and stirred for 30 minutes. At this stage, the microemulsion of the adduct [poly(vinlymethylether-co-maleic acid):(An)_(n)]was stabilized to an appropriate size in the acidic solution.

2.5 ml of 3% hydrogen peroxide (containing 0.022 mole H2O2) was addedslowly to initiate the polymerization of the adduct of aniline andPVME-MA. The reaction mixture soon become green in color. After vigorousstirring for 2 hours, the reaction mixture was poured through a filterpaper to remove a small amount of particles. The filtrate was a darkgreen homogeneous aqueous dispersion of the reaction product.

The suspension stability: The as-obtained solution remained homogeneousfor over one year without precipitation. The dispersed product does notflocculate in salt solutions such as 0.37 M of sodium sulfate indicatinggood stability against salting out.

The conductivity measurement.

The solution was purified through dialysis to remove unreacted anilineand other small ions. The purified aqueous solution was cast on a glassmicroslide and dried at 70° C. for 48 hrs. The thickness (t) of the filmwas estimated through the measurement of absorbance (A) at 800 nm (whenA-1, t=1 μm). Colloidal silver was coated over the cast film to makefour contact lines. The conductivity of the cast film was measuredthrough the standard four-probe method. As an example, A=1.1, t=1.1 μm,the distance d=1.0 cm, the width w=2.5 cm, the resistance R=1.3×10⁵Ω,the conductivity σ=d/Rtw=0.28S/cm.

The average conductivity value is reported in the Table set forth below.

EXAMPLE 4

PANI:P(VME-MA), r=2

Synthesis of PANI/PVME-MA(—COOH/An=1:2)

0.96 gm of poly(vinylmethylether-co-maleic acid) (containing 0.011 moleof carboxylic functional group Aldrich, M.W.=67,000) was dissolved in 25ml of distilled water. Then 0.022 mole aniline monomer was added. Awhite emulsion was formed. 5 ml of methanol was added to make a clearsolution and the solution was stirred for 1 hour. 25 ml 3M HCl and6.0×10⁻⁴ mole ferric chloride were introduced and then 0.022 molehydrogen peroxide was slowly added into the reaction mixture. Thereaction mixture soon become green colored. After vigorous stirring for2 hours, the reaction mixture was poured through a filter paper toremove small amount of particles. The filtrate was a dark greenhomogeneous aqueous solution.

The suspension stability: the as-obtained solution remained homogeneousfor over one year. The suspension remains stable when mixed with 0.37MNa₂SO₄.

The conductivity measurement

The product solution was purified through dialysis to remove unreactedaniline and other small ions. The purified aqueous solution was cast ona glass microslide and dried at 70° C. for 48 hrs. The thickness (t) ofthe film was estimated through the measurement of absorbance (A) at 800nm (when A-1, t=1 μm). The colloidal silver was coated over the castfilm to make four contact lines. The conductivity of the cast film wasmeasured through the standard four-probe method. As an example, A=0.6,t=0.6 μm, the distance d=1.2 cm, the width w=2.5 cm, the resistanceR=2.1×10⁴Ω, the conductivity σ=d/Rtw=0.038S/cm. The average conductivityvalue is reported in the Table below.

EXAMPLE 5

PANI:P(VME-MA), r=3

Synthesis of PANI/PVME-MA(—COOH/An=1:3)

0.96 gm of poly(vinylmethylether-co-maleic acid) (containing 0.011 moleof carboxylic functional groups, Aldrich, M.W.=67,000) was dissolved in25 ml of distilled water. Then 0.033 mole aniline monomer was added anda white emulsion was formed. 10 ml of methanol was added to make a clearsolution and the solution was stirred for 1 hour. Then 25 ml 3M HCl and6.0×10⁻⁴ mole ferric was added and 0.033 mole hydrogen peroxide wasslowly added. The reaction mixture soon became green colored. Aftervigorous stirring for 3 hours, the reaction mixture was poured through afilter paper to remove small amount of particles. The filtrate was adark green homogeneous aqueous solution.

The suspension stability

The as-obtained solution remained homogeneous for over one year. Thesuspension remained stable when mixed with 0.37M Na₂SO₄.

The conductivity measurement

The product solution was purified through dialysis to remove unreactedaniline and other small ions. The purified aqueous solution was cast ona glass microslide and dried at 70° C. for 48 hours. The thickness (t)of the film was estimated through the measurement of absorbance (A) at800 nm (when A-1, t=1 μm). The colloidal silver was coated over the castfilm to make four contact line. The conductivity of the cast film wasmeasured through the standard four-probe method. As an example, A=1.3,t=1.3 μm, the distance d=1.0 cm, the width w=2.5 cm, the resistanceR=9.0×10³Ω, the conductivity σ=d/Rtw=0.034S/cm. The average conductivityvalue is reported in the Table below.

EXAMPLE 6

PANI:P(VME-MA), r=4

Synthesis of PANI/PVME-MA(—COOH/An=1:4)

0.96 gm of poly(vinylmethylether-co-maleic acid) (containing 0.011 moleof carboxylic functional groups, Aldrich, M.W.=67,000) was dissolved in25 ml of distilled water. Then 0.044 mole aniline monomer was added anda white emulsion was formed. 12 ml of methanol was added to make a clearsolution and the solution was stirred for 1 hour. Then 25 ml 3M HCl and6.0×10⁻⁴ mole ferric chloride was added and 0.044 mole hydrogen peroxidewas slowly added. The reaction mixture soon became green colored. Aftervigorous stirring for 4 hours, the reaction mixture was poured through afilter paper to remove appreciable amount of particles. The filtrate wasa dark green homogeneous aqueous solution.

The next section describes examples of the chemical analysis of thereaction products to show that the expected r=N_(AN)/N_(COOH) values ofthe molecular complex are confined. The yield of the reaction was highenough that there was no significant amount of unreacted startingmaterials remaining in the water suspension of the final product. Thechemical analysis of the products formed in Examples 3 and 6 are used asan illustration of the procedure.

Chemical composition of the molecular complex

The following steps were carried out for the chemical analysis:

1. Purify the reaction product to remove any unreacted starting materialand any side reaction products. The resulting samples contain only thepolymeric complex.

2. Perform elemental analysis on the purified sample to verify that theelemental composition matches with the expected r value.

3. Perform spectroscopic analysis to show the purified sample containsthe functional groups expected of the polymeric complex.

4. Examine the physical properties of the purified sample to show thatthe physical properties are consistent with that of a polymeric complex.

Purification of the product

The product solutions may contain free polyelectrolyte, un-complexedPANI, unreacted aniline, low-molecular weight oligomers and inorganicions. In order to be certain that all the characterization and elementalanalysis are performed on samples free of the above-mentionedimpurities, a purification was performed that involved filtration, ionexchange, extraction and dialysis.

1. Removal of uncomplexed polyaniline

The uncomplexed polyaniline is known to aggregate into insolubleparticles. If there were significant amount of uncomplexed single-strandpolyaniline in the product, the solution would contain insolubleparticles. The reaction product was found to be a homogeneous greenliquid without any visual evidence of suspended particles orprecipitates. When the solution of the product formed in example 3 (orfrom Example 6) is filtered through a filter paper, there was anegligible amount of solid particles remained in the filter paperindicating that most polyaniline formed is in the polymeric complex. Thefiltrate is free from uncomplexed single-strand polyaniline, and is usedfor the next step of purification.

2. Removal of ionic impurities

Ferric and ferrous ions used as catalysts were removed by passing thecomplex solution through a column of cationic ion exchange resin(AMBERLITE IR-120 H). The effectiveness of this removal process wasmonitored spectroscopically using potassium thiocyanate as indicator.Before ion exchange the sample has a UV absorption spectrum that showsthe characteristic absorption band at 470 nm indicating the presence offerric thiocyanate. After the ion exchange, the 470 nm absorption bandwas eliminated indicating that the ferric ions were removed.

Since the solution is acidic, any “free” unreacted anilineor the smallmolecular weight “free” oligomer of aniline (not bound to the molecularcomplex) should be in the protated form. These anilinium ions wereremoved by dialysis against 0.2 M hydrochloric acid solution and thenagainst distilled water. The dialysis membrane SPECTRA/POR has amolecular weight cutoff at 3,500.

3. Removal of free poly(vinylmethylether-co-maleic acid)

The uncomplexed poly(vinyl methyl ether-co-maleic acid), PVME-MA, isseparated from the molecular complex by exploiting the difference ofsolubility of these two polymers in an acetonitrile/water mixture. Asolubility test was done to establish the solubility difference. It wasfound that PVME-MA is soluble in the acetonitrile/water mixture of anyproportion, while the [polyaniline:poly(vinylmethylether-co-maleicacid), r=1 to 4] complex is insoluble in pure acetonitrile but isdispersible in a water/acetonitrile mixture that contains less than 75%(by volume) of acetonitrile. The complex precipitates in water mixturewith more than 75% of acetonitrile. Thus, the free poly(vinyl methylether-co-maleic acid) PVME-MA is extracted by an appropriatewater/acetonitrile mixture that extracts PVM-MA but precipitates thepolymeric complex.

50 ml of the product aqueous solution three times volume of acetonitrile(150 ml) was added to the aqueous dark green complex solution resultingin a dark green precipitate. The precipitate was filtered. If theprecipitate is immediately stirred in water, the complex may beredispersed in water and then reprecipitated with three times volume ofacetonitrile. The process of dissolution and precipitation was repeatedthree times until on vaporation of the filtrate no residue remains inthe evaporation dish, and the weight of the dried precipitate remainsconstant. Sometimes, the precipitate from acetonitrile-water mixture wasnot redispersible in water. In this case, the solid complex was soakedin the mixed solvent of acetonitrile and water and agitated with amagnetic stirrer. The process of filtration and soaking in fresh mixedsolvent of acetonitrile and water (3:1 or 4:1) was repeated four timesuntil no residue is left on evaporation of the filtrate and there is nochange of the weight of the dried solid complex.

4. Removal of unreacted aniline and oligomers.

To remove the anilinium ions attached to the complex, the sample istreated with a strong base. Under this condition An is released from thecomplex.

When an excess amount of 1N NaOH solution is added the green-coloredsolution turns purpose-colored depotonated form. To remove the releasedaniline and NaOH, the purple colored solution is dialyzed with adialysis tube (SPECTRA/POR, molecular weigh cutoff at 3,500) againstdistilled water. The water outside the dialysis tube is analyzedspectroscopically. At the end of dialysis, the purpose colored solutionin the dialysis tube turns blue.

The blue colored solution is treated with 0.2M HCl to change back togreen colored protonated form. During the cycle of deprotonation andprotonation, the polymer conformation of the molecular complex wassignificantly changed. This conformational change may lead to theexposure of the aniline oligomers originally held by the molecularcomplex in its hydrophobic pockets. It was found that a small additionalamount of aniline and oligo-aniline was removed by this step. The greensolution is then subject to repeated dialysis against water to removethe excess HCl until the water outside the dialysis tube is negative tosilver nitrate test, which shows the absence of Cl⁻ ions. The water isalso analyzed spectroscopically and no detectable anilium ions arefound.

Compositions Analysis supports the complex formation

The sample purified in the manner described in the preceding section isfree from any un-reacted starting materials (aniline and PANI:PVME-MLA),any aniline oligomers, any uncomplexed polyaniline or small ion salts.Samples were dried in oven at 70° C. for 72 hours before sealing inair-tight sample vials. Elemental analyses were performed by M-H-WLaboratories, Phoenix, Ariz. The purified sample form the product ofExample 3 has an elemental content of C: 60.15% H: 5.87% and N: 7.39%,giving an empirical formula of (C₇H₁₀O₅)_(0.50): (C₆H₄NH)_(1.00):H_(1 . . . 12)O_(0.65) which is consistent with the theoretical formula(C₇H₁₀O₅)_(0.050): (C₆H₄NH)_(1.00): (H₂O)₂ for [PANI:PVME-MLA, r=1).Note that each monomer unit of the poly(vinylmethylether-co-maleicacid), or C₇H₁₀O₅), contains two carboxylic acid thus the chemicalformula is consistent with r=N_(AN)/N_(—COOH)=1. The presence water inthe elemental analysis result is expected because the polymer ishygroscopic. At the temperature of drying 70° C.) the water moleculesbound to the ionic group are not removed. Based on the fact that theaverage molecular weight of PVME-MLA is 67,000 which consists of about385 units of (vinyl methyl) ether-maleic acid), this complex has thefollowing formula: (C₇H₁₀O₅)₃₈₅: (C₆H₄NH)₇₇₀. Here we use an averagedegree of polymerization in this formula. There is a distribution ofchain length for both polymer strands.

The purified sample form the product of Example 6 has an elementalcontent of C: 59.18%, H: 4.16% and N: 9.98%, which is consistent with anempirical formula of (C₇H₁₀O₅)_(0.13): (C₆H₄NH)_(1.00). This empiricalformula agrees with what is expected for [PANI:PVME-MLA, r=4]. Based onthe fact that the average molecular weight of PVME-MLA is 67,000 whichconsists of about 385 units of (vinyl methyl ether-maleic acid), thiscomplex has the following formula: (C₇H₁₀O₅)₃₈₅: (C₆H₄NH)₂₉₆₂. It isquite likely that the polyaniline component of the complex is not asingle polymer chain with a degree of polymerization of 2962, but ratheran aggregate of several shorter chains that are collectively complexedwith the poly(vinylmethylether-co-maleic acid).

The percentage of hydrogen atom in the polyaniline component in thecomplex is dependent on the degree of oxidation. A sample with higherdegree of oxidation may contain higher percentage of quinone-diimineunit (—Ph—N═Q═N—) which has less hydrogen atoms per unit than anaromatic diamine unit (—Ph—NH—Ph—NH—). Here Q stands for a quinonestructure and Ph stands for a phenyl ring. The amount of water moleculesbound to the polymer complex is weakly dependent on the extent ofdrying. Taking these uncertainties into account, the results of theelemental analysis are consistent with the expected chemicalcomposition.

Samples were also synthesized without the complexing polyelectrolyte.This yields the conventional single-strand polyaniline. These sampleswere also submitted to M-H-W Laboratories for elemental analysis as partof blind tests to check the reliability of the elemental analyses.Elemental analysis of the purified base form of single-strandpolyaniline gives C: 76.21%, H: 5.09%, N: 5.81% the correspondingempirical formula if C₆H_(4.81)N_(1.01). The expected formula for thefully reduced polyaniline base is C₆H₅ N. However, the stablepolyaniline can exist in an oxidized form with variable extent ofoxidation. The most oxidized form has the theoretical formula of C₆H₄N.The sample of pure poly(methyl vinyl ether-co-maleic acid) was submittedfor elemental analysis to give C: 49.61%, H: 5.77% while the theoreticalcomposition is C: 48.26%; H: 5.80%. Thus the elemental analysis resultis reliable.

The result of elemental analysis indicates that the synthesized productshave chemical composition which is consistent with the formation of themolecular complex with the expected r values.

Infrared analysis of the purified molecular complex

The infrared spectrum of PANI:PVME-MLA shows that the reaction productcontains functional groups from both PVME-MLA part (—COOH) and from thepolyaniline (C—N and aromatic rings). The band at 1718 cm⁻¹ isattributed to the stretch mode of carbonyl group of carboxylic acid onPVME-MLE; a strong band at 1160 cm⁻¹, which is characteristic ofconducting polyaniline can also be identified. The unusual band around2360 cm⁻¹ is due to CO₂ in the air. The bands at 1580 cm⁻¹ areattributed to the ring stretching combined with C—N stretching. The bandat 1263 cm⁻¹ is assigned to C—N stretching mixed with C—H bonding. Thusthe IR spectrum clearly shows IR features of a molecular complex, i.e.co-presence of unique features from PVME-MLA and PANI.

Polymeric complex:evidences from the physical properties.

Physical properties of our molecular complex are expected to bedifferent from the single-strand polyaniline. WE synthesize both thecomplex and the single strand PANI under the same reaction condition andexamine their difference in properties. To demonstrate that twodifferent products are formed, one from the unusual aniline chemicalpolymerization and the other from the template-guided anilinepolymerization in the presence of maleic acid copolymers, two parallelpolyaniline syntheses are run, in which the synthetic conditions and allthe reagents are identical except the absence of presence of maleic acidcopolymers.

Comparison with the prior art polyaniline:HCl salt

The following Examples compare the properties of the polymeric complexesof examples 1-6 with the prior art molecular complexes (polyaniline:HClsalt).

EXAMPLE 7

Synthesis of single stranded (chloride doped) polyaniline

0.011 mole aniline monomer (Aldrich, redistilled) was added to 50 ml 1.5M HCl. Subsequently, 6.0×10⁻⁴ mole ferric chloride was added followed by0.011 mole hydrogen peroxide (30%, Fisher Scientific). The reactionmixture soon became green-colored and dark-green solid particlesprecipitated. After continued stirring for two hours, a dark greenprecipitate was deposited on the bottom with the supernatant liquidbeing brownish red.

Comparison 1

Different properties of single-stranded polyaniline (Example 7) and thepolymeric complexes synthesized in Examples 1 to 6:

The most apparent and striking different between Polyaniline synthesizedby the conventional method (Example 7, yields strand PAN;HCl) and by themethod described in Examples 1-6 (yielding double-strand polyaniline) isthat their solubility (or dispersibility) in aqueous solutions. thedouble-strand [PAN:PAA, r=1 or 1.5] and [PAN:PVME-MA] are stableemulsions in water, but the single PAN:HCl is insoluble in water. Inaddition, the double strand polyanilines are more resistant to dedopingby either heat or water. The single-strand PAN:HCl dedopes easily byheating or immersion in pH neutral water.

Comparison with the prior art molecular complexes.

The r ratio of he prior art molecular complex was limited to r≦1.

The preceding Examples 1-6 show materials where r=1, 2, 3 and 4. Thisrange of ratios has not been reported previously. This range of ratiosis advangeous because the materials with higher r values are materialswith higher electrical conductivity. The reaction products of Examples1-6 are stable in aqueous solution. The water-borne high-conductivitymaterials of the invention have advantageous over the traditionalpolyaniline:HCl material due to its processability in coating and dyeingapplications.

If the r value is increased beyond 1 for the molecular complexes andusing the syntheses disclosed in the prior art, the resulting product isnot stable in aqueous solution or conventional solvents. Examples 1-6support that the polymeric complexes of the present invention can have ahigh r value while being stable in an aqueous medium.

The water-borne molecular complexes with r≦1 of this invention aresynthesized by a procedure that is not obvious in view of the prior artof U.S. Pat. No. 5,489,400. In the synthesis of Examples 1-6, thepolyelectrolyte functions not only as a template for binding themonomers of aniline, but also serves as an emulsifier for the adductpolyelectrolyte:)An)_(n). The formation of the emulsified adductpolyelectrolyte:(An)_(n) is, however, not the only requirement. In orderfor the polymerized product [polyaniline:polyelectrolyte, r≧1] to bestabely suspended in water, the particle size of the emulsified adductpolyelectrolyte:(An)_(n) needs to be sufficiently small. Examples 1-6show that the use of methanol-water mixed solvent leads to the product[polyaniline:polyelectrolyte, r≧1] which is a stable, latex-like,water-borne suspension. We theorize that the methanol contained in thewater solution helps to reduced the size of the macro-emulsion of theprecursor polyelectrolyte: (An)_(n) as evidenced form th change of lightscattering of the solution from white color to nearly transparent. Theutilization of the mixed water-methanol solution is a simple, butsubtle, manipulation described in the steps 1 and 2 of Example 1.

In the following examples synthesis (referred to as Procedure B) issubstantially similar to that described in Examples 1-6 (which will bereferred to as Procedure A) except neglecting the addition of methanoland the associated controls of the emulsion. These examples show thatalthough Procedure B may sometimes lead to water soluble reactionsproducts for r≧1, unlike that of Procedure A, the products alwaysprecipitates out of the solution if r≧1.

Comparison 2: Properties of the polymeric complexes synthesized byProcedure B

This comparison experiment was performed in parallel with theexperiments described in comparison #1 and Examples 1-6. Theconcentrations, the volumes of all chemicals used were the same exceptthat the amount (moles) of different polyelectrolytes (templates) werevaried for these comparative syntheses. The polyelectrolytes used forthe comparisons were poly(acrylic acid) (PAA) and poly(styrene sulfonicacid) (PSSA).

EXAMPLE 8

Synthesis of [PANI;PAA, r=0.5] by Procedure B

1 gram (0.011 mole) of aniline monomer was added to an aqueous solutionof poly(acrylic acid) (Aldrich, M.W.=90,000 25 wt. % solution in water)containing 0.022 mole of carboxylic acid functional groups to provide awhite gel. The white gel was dissolved in 25 ml of distilled water andto form a homogeneous solution which was stirred for 2 hours. 25 ml of3M HCl and 6.0×10⁻⁴ mole ferric chloride was added followed by the slowaddition of 0.011 mole of hydrogen peroxide. The reaction mixture soonbecame green colored. After vigorous stirring for 2 hours, the reactionmixture was poured through a filter paper. The filtrate was a dark greenhomogeneous aqueous solution. Note that this produce has a r value of0.5 and is suspendable in water.

EXAMPLE 9

Synthesis of [PANI:PAA, r=1] by Procedure B

0.022 mole of aniline monomer was added to an aqueous solution ofpoly(acrylic acid) (Aldrich, M.W.=90,000 25 wt. % solution in water)containing 0.022 mole of carboxylic acid functional groups to provide awhite gel. The white gel was dissolved in 25 ml of distilled water andthis homogeneous solution was stirred for 2 hours. 25 ml of 3M HCl and6.0×10⁻⁴ mole ferric chloride was added followed by the slow addition of0.022 mole of hydrogen peroxide. The reaction mixture soon become greencolored. After vigorous stirring for 2 hours, a dark green precipitateformed with the supernatant liquid being brownish red.

This produce with r=1 is not suspendable in water. This is in contrastwith the water-borne product of Example 1.

EXAMPLE 10

Synthesis of [PANI:PAA, r=2] by Procedure B

0.022 mole of aniline monomer was added to an aqueous solution ofpoly(acrylic acid) (Aldrich, M.W.=90,000 25 wt. % solution in water)containing 0.011 mole of carboxylic acid functional groups to provide awhite emulsion. 5 ml of methanol was added to make a clear solution andthis homogeneous solution was stirred for 2 hours. 25 ml of 3M HCl and6.0×10⁻⁴ mole ferric chloride was added followed by the slow addition of0.022 mole of hydrogen peroxide. The reaction mixture soon became greencolored. After vigorous stirring for 2 hours, a dark green precipitateformed with the supernatant liquid being brownish red.

EXAMPLE 11

Synthesis of [PANI:PSSA, r=0.5] by Procedure B.

0.011 mole of aniline monomer was added to an aqueous solution ofpoly(styrene-sulfonic acid) (Polysciences, M.W.=70,000 30 wt. % solutionin water) containing 0.022 mole of sulfonic acid functional groups toprovide a white gel. The white gel was dissolved in 25 ml of distilledwater and this homogeneous solution was stirred for 2 hours. 25 ml of 3MHCl and 6.0×10⁻⁴ mole ferric chloride was added followed by the slowaddition of 0.011 mole of hydrogen peroxide. The reaction mixture soonbecome green colored. After vigorous stirring for 2 hours, the reactionmixture was poured through a filter paper to remove small amount ofparticles. The filtrate was a dark green homogeneous aqueous solution.

EXAMPLE 12

Synthesis of [PANI:PSSA, r=1.0] by Procedure B

0.022 mole of aniline monomer was added to an aqueous solution ofpoly(styrene-sulfonic acid) (Polysciences, M.W.=70,000 30 wt. % solutionin water) containing 0.022 mole of sulfonic acid functional groups toprovide a white gel. The white gel was dissolved in 25 ml of distilledwater and this homogeneous solution was stirred for 2 hours. 25 ml of 3MHCl and 6.0×10⁻⁴ mole ferric chloride was added followed by the slowaddition of 0.022 mole of hydrogen peroxide. The reaction mixture soonbecame green colored. After vigorous stirring for 2 hours, a dark greenprecipitate formed with the supernatant liquid being brownish red.

EXAMPLE 13

Synthesis of [PANI:PSSA, r=1] by Procedure B.

0.022 mole of aniline monomer was added to an aqueous solution ofpoly(styrene-sulfonic acid) (Polysciences, M.W.=70,000 30 wt. % solutionin water) containing 0.011 mole of sulfonic acid functional groups toprovide a white emulsion. 5 ml of methanol was added to make a clearsolution and this homogeneous solution was stirred for 2 hours. After 25ml of 3M HCl and 6.0×10⁻⁴ mole ferric chloride was added followed by theslow addition of 0.022 mole of hydrogen peroxide. The reaction mixturesoon became green colored. After vigorous stirring for 2 hours, a darkgreen precipitate formed with the supernatant liquid being brownish red.

Properties of the reaction products synthesized by Procedure B

Although the complexes with low loading of aniline (r<1) is soluble, butfunctional groups to aniline units) are substantially the same, it isquite different when the aniline loading is high.

The properties of the conducting polymers synthesized in Examples 1-13are summarized in the followings:

[PAN:PVME-MA, r=1 to 4 ] synthesized by Procedure A is a stable emulsionin water. A coating formed by drying the emulsion is not redissolved inwater. It can be used as a water-borne coating material.

[PAN:PAA, r=1 to 1.5] synthesized by Procedure A is a stable emulsion inwater. A coating formed by drying the emulsion into a film. The film isnot redissolvable in water. It can be used as a water-borne coatingmaterial.

[PAN:PAA, r=0.5] and [PAN:PSSA, r=0.5] synthesized by either Procedure Aor B are soluble in water. A coating formed by drying the solution doesnot stay as a coating when immersed in water. It swells and is partiallyredispersed in water. These materials will not form a durable coating incontact with water or moisture.

[PAN:PAA, r≦1] and [PAN:PSSA, r≦1] synthesized by Procedure B is not astable emulsion or a solution in water. It can be used as a water-bornecoating material.

The single strand PAN:HCl is not soluble or dispersible in water. It cannot be used as a water-borne coating material.

From these data on the material properties, it can be seen that onlyProcedure A leads to superior water-borne conducting polymers that aresuitable for coating applications. The product, when synthesized byProcedure A, is a stable emulsion. The dried film formed after coatingis not attacked by water or moisture.

The utility of the products synthesized by Procedure A are not limitedto water-borne coating applications. Some of the products are soluble inorganic polar solvents or water/solvent mixtures for non-aqueous coatingapplications. The products may also be blended with other polymers suchas Nylon 6-12, Nylon 6-6, poly(vinyl butyral), epoxy, alkyd, etc. forvarious antielectrostatic, anticorrosion and optical applications.

Conductivity Difference

TABLE r value 0.5 1 2 3 4 5 PAN:P(MVE-MA) 10⁻⁷ S/cm 0.2 S/cm 0.2 S/cm0.1 S/cm 1 S/cm 1 S/cm PAN:PAA 10⁻⁷ S/cm 0.2 S/cm 0.2 S/cm 0.1 S/cm 1S/cm 1 S/cm Conductive polymers Surface resistivity on thin filmsThickness = 10⁻³ cm PAN:P(MVE-MA), r = 0.5 10¹⁰ Ohm/□ PAN:P(MVE-MA), r =1 5 × 10³ Ohm/□ PAN:P(MVE-MA), r = 3 10⁴ Ohm/□

High r-value material obtained by synthesis.

To synthesize PANI/PVME-MA with the mole of ratio of acidic functionalgroups to aniline monomers 1:2, 1:3, or 1:4 a mixed solvent of methanoland water is used to provide a homogeneous reaction mixture. Thepolymerization of aniline in the mixed solvent of methanol and waterproceeds smoothly as long as the content of methanol is lower than 50%.When the percentage of methanol is greater than 90%, no aniline ispolymerized.

In the preferred embodiment of the invention, a conducting polymer ispolyaniline and the polyelectrolyte is an anionic copolymer. Polyanilinecarries the electrical or optical properties and the anionic copolymeris used as a vehicle to optimize structural features that are needed forprocessability and durability. The anionic copolymers preferably usedinclude random copolymers, poly(acrylamide-co-acrylic acid) (PAAM-PAA)with acrylic acid contents of 90%, 70%, 40% and 10%, and alternatingcopolymers, i.e. poly(ethylene-co-maleic acid) (PE-MLA) andpoly(vinylmethylether-co-maleic acid) (PVM-MLA).

EXAMPLE 14

Materials

PANI/P(VME-MLA) (An/—COOH=2:1) was synthesized following the procedurepreviously described for Example 4. Nylon 6/12 and nylon fabrics wereobtained from Monsanto.

Measurements

UV-visible spectra were obtained on PERKIN-ELMER Lambda 2 UV/VISSpectrophotomer.

The conductivity of nylon fabrics and solid cast films on glass stripwas measured through a modified 4-probe method. Four silver lines weremade equally spaced on the film using a conductive colloidal silverpaste. Current (measured by Keithley 197A autoranging microvolt DMM) waspassed through two inner silver lines while the voltage drop wasmeasured across two outer silver lines with Potentiostat/GalvanostatHA-151.

A piece of white nylon fabric, commonly used for clothings, was soakedin the aqueous dispersion of PANI/PVME-MLA for 20 minutes, taken out ofthe solution, rinsed with distilled water and air-dried. This processwas repeated twice and uniform green colors fabrics are obtained.

No visible solid particles were deposited on the surface. The fabric wasstill soft and flexible and no changes in any mechanical properties ofthe fabric were observed. The surface resistivity of the dyed nylonfabrics were measured as low as 5×10³ ohm/square, much lower than 10⁹ohm/square which is the surface resistivity of state-of-the-artantielectrostatic coating.

This piece-dyeing process just described did not provide a completepenetration of PAN:PVME-MA into the fabric. However, it was industriallyfeasible process to deposit a uniform, smooth, coherent film of theconductive polymer onto individual fibers of the nylon fabric. The filmwas resistant against water washing cycles and no decrease ofconductivity was found with repeated washings. This supports that thePANI/PVME-MLA adheres strongly to the nylon fabric most likely due tohydrogen bonding between PVME-MLA strand and the nylon.

The fact that the connectivity of dyed fabric remain unchanged afterrepeated water washings also means that this fabric is more resistantagainst deprotonation induced transition from conductive state toinsulating state. Single strand conventional polyaniline changes fromconductive state to insulating state at pH around 4 while PANI/PVME-MLAremains conductive until the pH is around 8.5.

The conductivity of the dyed fabrics is less sensitive to humidity thanthe usual ionic antielectrostatic coatings because conducting polymersare electronic conductors. Although higher humidity leads to higherconductivity, the conductivity of conducting polymer does not rely onthe humidity.

The low r value polymeric complexes synthesized by Procedure B inExample 8 for [PAN:PAA, r=0.5] and Example 11 for [PAN:PSSA, r=0.5] werealso used as a dyeing agent for comparison purpose. It was found thatthe stained fabrics when dried, have low conductivity because of the lowr values. It was also found that the dyes with r=0.5 are easilyredissolved in water and is lost by washing the fabrics.

Electrically conductive polymer blend of PAN:PVME-MLA with Nylon

Nylon 6/12 is readily dissolved in formic acid to give a colorlesshomogeneous solution. The as-synthesized PANI/PVME-MLA is in aqueoussolution. PANI/PVME-MLA as dried powder in a formic acid solution ismixed with concentrated nylon 6/12 formic acid solution (18.2% wt) anddark green fine particles appear, indicating the thermodynamicincompatibility of PANI/PVME-MLA with nylon 6/12. When 4.0% by weightPANI/PVME-MLA is mixed with 1.8% by weight nylon 6/12 in formic acid(based on total weight of solution) a homogeneous solution is obtained.However, the cast film from the above solution is macroscopicallyinhomogeneous.

A formic acid blend solution (with fine dark green particles) of nylon6/12 and PANI/PVME-MLA is precipitated when added to water. Thedistilled blend dissolves in formic acid very readily. After stirringfor 72 hours, a dark green homogeneous solution is obtained. The castfilm of the solution on glass is very homogeneous and transparent. Thereason for the formation of at least macroscopically homogeneous blendis not completely understood. It is speculated that PANI/PVME-MLA maymore or less associate or even form a three-component complex nylon6/12.

The FIGURE shows the electrical conductivity (σ) versus weight fraction(f) of the PANI/PVME-MLA complex in polyblends with nylon 6/12. Theconductivity, rather than being a linear function of loading, risesdramatically as the percolation threshold (f=0.1) is reached. Theconductivity at=30% loading is essentially the same as that of the purePANI/PVME-MLA.

When an electrically conducting material-metal or carbon powder orfilaments are mixed with an insulating polymer, essentially no increasein conductivity is observed until particles of the conducting materialfirst touch each other and thus form a conducting pathway throughout themixture. At this loading level “percolation threshold” (=16 vol. % for athree-dimension network of conducting globular aggregates in aninsulating matrix) the conductivity increases extremely rapidly. Thepercolation threshold is greatly dependent on the size and aspect ratioof the particles-whether, for example, spheres or long needles-and canvary from a few volume percent up to 30% to 40% or more in industrialcomposites depending on the efficiency of mixing and uniformity of size.However, in blends of doped polyaniline and also in blends ofderivatives of certain substituted polythiophenes in conventionalinsulating polymers either no or only very low (<5%) percolationthresholds are observed.

The relatively large percolation threshold observed with the blend ofPANI/PVME-MLA with nylon 6/12 can be explained in terms of wettabilityor compatibility. The surface tension difference between two componentsis small or the two components are quite compatible so that PAN:PVME-MAtends to distribute itself homogeneously in nylon 6/12 matrix. Comparedwith aggregation of the conductive fillers in insulating matrix, theeven distribution leads to lower conductivity and higher percolationthreshold since the former will afford many more interparticle contacts.

Conductive blends of PAN:PVME-MA and nylon 6/12

The fundamental requirement for creating conducting polyblends is theneed for a solvent in which both the conducting polyaniline complex andthe desired bulk polymer are co-soluble. Given such a solvent,conducting polyblends can be made by co-dissolving the polyanilinecomplex and the bulk polymer at concentration such that when cast fromsolution, the resulting blend will have the desired ratio of conductingpolyaniline complex to bulk polymer. The conducting polyblend materialcan be fabricated into useful shapes (film, fiber, etc.) throughstandard methods for solution processing (e.g., fiber-sprinning,spin-casting, dip-coating, etc.). In addition, since polyaniline isrelatively stable at high temperatures, the conducting polyblends can bemelt-processed.

The foregoing description has been limited to a specific embodiment ofthe invention. It will be apparent, however, that variations andmodifications can be made to the invention, with the attainment of someor all of the advantages of the invention. Therefore, it is the objectof the appended claims to cover all such variations and modifications ascome within the true spirit and scope of the invention.

Having described our invention, what we now claim is:
 1. A processableelectrically conductive polymeric complex, the polymeric complex beingwater-borne and comprising a polyelectrolyte having acid functionalgroups and a conductive polymer, the conductive polymer selected fromthe group consisting of polyaniline, polypyrrole, polythiophene,poly(phenylene sulfide), the conductive polymer ionically bound to thepolyelectrolyte and wherein the mole ratio of the monomers which formthe conductive polymer to the acid functional groups of thepolyelectrolyte is ≧1, the polymeric complex being made by atemplate-guided chemical polymerization process comprising adsorbing themonomers onto the polyelectrolyte in a mixture of alcohol and water toform a polyelectrolyte adduct, emulsifying the polyelectrolyte adduct inan acid to form an emulsified polyelectrolyte adduct and oxidativelypolymerizing the emulsified polyelectrolyte adduct to form the polymericcomplex, the polymeric complex being water insoluble when dried as acoating on a substrate.
 2. The polymeric complex of claim 1 wherein thealcohol is methanol and the substrate is glass.
 3. The polymeric complexof claim 1 wherein the polyelectrolyte is selected from the groupconsisting of poly(acrylic acid) (PAA), poly(vinylmethylether-co-maleicacd)(PVME-MA), poly(vinylalkylether-co-maleic acid) and poly(ethylene-co-maleic acid).
 4. The polymeric complex of claim 1 whereinthe conductive polymer is polyaniline and the polyelectrolyte ispoly(vinylmethylether-co-maleic acid).
 5. The polymeric complex of claim1 wherein the mole ratio of the monomers to the financial groups is 1.6. The polymeric complex of claim 1 wherein the mole ratio of themonomers to the functional groups is 1.5.
 7. The polymeric complex ofclaim 1 wherein the mole ratio of the monomers to the functional groupsis
 2. 8. The polymeric complex of claim 1 wherein the mole ratio of themonomers to the functional groups is
 3. 9. The polymeric complex ofclaim 1 wherein the mole ratio of the monomers to the functional groupsis
 4. 10. The polymeric complex of claim 1 wherein the polyelectrolyteis an anionic copolymer.
 11. An electrically conducting fabriccomprising a polymeric complex admixed with fibrous material comprisedof fibers, the polymeric complex being water-borne and comprising apolyelectrolyte having acid functional groups and a conductive polymerselected from the group consisting of polyaniline, polypyrrole,polythiophene, poly(phenylene sulfide), the conductive polymer ionicallybound to the polyelectrolyte and wherein the mole ratio of the monomerswhich form the conducting polymer to the acid functional groups of thepolyelectrolyte is ≧1, the polymeric complex admixed with fibersselected from the group consisting of Nylon 6-12, Nylon 6-6, poly(vinylbutyral), epoxy and alkyd in an amount of up to 16% percolationthreshold by volume based on the total volume of the electricallyconductive fabric, the polymeric complex being made by a template-guidedchemical polymerization process comprising adsorbing the monomers ontothe polyelectrolyte in a mixture of alcohol and water to form apolyelectrolyte adduct, emulsifying the polyelectrolyte adduct in anacid to form an emulsified polyelectrolyte adduct and oxidativelypolymerizing the emulsified polyectrolyte adduct, the polymeric complexbeing water insoluble when dried as a coating on the fibrous material.12. The polymeric complex of claim 11 wherein the alcohol is methanol.13. The polymeric complex of claim 11 wherein the polymeric complex isinsoluble in water when admixed with the fibers and dried.
 14. Thepolymeric complex of claim 11 wherein the polyelectrolyte is selectedfrom the group consisting of poly(acrylic acid) (PAA),poly(vinylmethylether-co-maleic acid)(PVME-MA),poly(vinylalkylether-co-maleic acid) and poly (ethylene-co-maleic acid).15. The polymeric complex of claim 11 wherein the conductive polymer ispolyaniline and the polyelectrolyte is poly (vinylmethylether-co-maleicacid).
 16. The polymeric complex of claim 11 wherein the mole ratio ofthe monomers to the functional groups is
 1. 17. The polymeric complex ofclaim 11 wherein the mole ratio of the monomers to the functional groupsis 1.5.
 18. The polymeric complex of claim 11 wherein the mole ratio ofthe monomers to the functional group is
 2. 19. The polymeric complex ofclaim 11 wherein the mole ratio of the monomers to the functional groupsis
 3. 20. The polymeric complex of claim 11 wherein the mole ratio ofthe monomers to the functional groups is
 4. 21. The polymeric complex ofclaim 11 wherein the polyelectrolyte is an anionic copolymer.